When I got married in my 20's (in 1977) although we had a reasonable number of guests the oldest person present (apart from the vicar and the organist) will have been under 30.
Why?
In the three years prior to getting married we lost all four parents (two in a motorway crash, one in a accident on the farm and one with cancer). Since all four were only children (unusual for all four to be surely!) there were no older relatives to attend because err, there were no older relatives.
Our wedding photos look very strange with none of the multi-generational images that we see elsewhere. It still hurts even after so many years.